Drum type brakes, rather than disc brakes, are generally used in trailer brake systems because brake actuators currently used do not develop sufficient pressure to actuate disc brake systems. The maximum pressure developed in these brake actuator devices is about 700 pounds per square inch (psi).
Disc brake systems are highly desirable because the braking force that can be developed is much greater than on a drum brake system. In trailer applications, there is a need for the greater braking capacity offered by disc brakes.
U.S. Pat. No. 3,796,287 discloses a surge type brake actuator for actuating hydraulically actuated brakes on a towed vehicle. The surge actuator assembly includes a telescoping housing assembly connected intermediate the ends of a tongue assembly. The housing has an outer tubular member connected to one portion and an inner tubular member connected to another portion of the tongue assembly and includes apparatus for providing force multiplication whereby an increased fluid pressure output can be obtained particularly for disk brake actuation. The force multiplication apparatus includes a toggle linkage system and a cam that actuates the joint of the toggle linkage. A shock absorber is interposed in the apparatus for providing a smoother brake operation.
A trailer tongue must support the "tongue weight" of the trailer. A trailer should be loaded so that the coupler on the trailer tongue is urged downwardly toward the hitch on the towing vehicle. Tubular members mounted in telescoping relation do not efficiently carry transverse loading without binding. Telescoping tubes, carrying a heavy tongue load transversely to the sliding joint is difficult to maintain in an efficient operating condition.
Apparatus is disclosed in U.S. Pat. No. 5,036,956 for use with tractor-trailer organizations in which a rotor is mounted fixedly and rotatably with a rear axle extending longitudinally and exteriorly of a rear axle housing, wherein the rotor includes a plurality of calipers. The calipers are actuated by a master cylinder positioned adjacent the rear axle and mounted on the axle housing. A torsion bar transmits rotative force from a remotely positioned pneumatic booster cylinder to the master cylinder utilizing cam collars mounted on the torsion bar for the master cylinder and pneumatic booster assembly.
A need exists for an inexpensive durable disk brake actuator that does not require use of pneumatic boosters or complex mechanisms for use on utility trailers, boat trailers, house and travel trailers and the like.